Dental restorations are used as permanent implants to fill the damage from dental cavities or from other causes. Commonly used dental restorations include inlays, onlays, dentinal pins and root pins. For example, an inlay is used to fill a tapered recess defined across an upper portion of a tooth. Dental restorations can be made of various durable materials including metals, composites, ceramics and porcelains and can be molded or machined. The quality of the dental restoration is typically related to its shape, its aesthetics and its durability.
Known methods and systems for making dental restorations such as inlays and onlays typically involve creating the dental restoration from a model or mold in a remote lab. The patient takes an appointment for a first visit with his dentist during which the dentist takes an impression of the missing dental tissue. In the case of some restorations, the dentist then fills the damaged region with a temporary fill material. In some cases, these manipulations require anesthesia. The patient then returns home with the temporary fill and the impression is sent to a remote lab where the dental restoration is made by a lab technician, using the impression. The dental restoration is then sent to the dentist.
The patient then takes another appointment for a second visit with his dentist. Some temporary fills have been known to fail between the two visits. In the second visit, the dentist can remove the temporary fill and prepare the damaged region of the tooth to receive the dental restoration. In some cases, this requires a second anesthesia. It is often required that the dentist make final adjustments to the dental restoration to adapt the contours of the restoration to the opposite teeth when the jaw is closed. In some cases, due to occurrence of errors stemming from the several manipulations by the dentist and/or by the remote lab technician, the restoration does not fit, and the process has to be repeated.
One of the latest techniques is the use of inlay-onlays prepared using 3D software such as, for example, the CEREC system from Sirona. The method consists in coating the tooth with a white powder and using a 3D imaging camera to upload a 3D representation of the tooth into a computer for executing a virtual restoration. The data obtained from the virtual restoration is stored in a file and is sent to a milling machine. The inlay-onlay is then milled out of a solid ceramic or composite block. Most inlay-onlays are made tooth-colored porcelain. However, these systems have some important drawbacks, mainly:                the milling tool drill bits and block may break because of increased strain against the block, forcing the user to change them often;        necessitate dentists to digitally create the model from scans, which is time consuming and requires computer-aided design (CAD) skills for which dentists are not normally trained;        having to use a CAD platform in order to generate a tool path is very complex; and        the complex environmental constraint in which the 3D data is obtained with the help of an intra-oral scanner doesn't allow for accurate measurement of the occlusal, therefore creating inaccuracies in the finished restoration.        
The known methods and systems described above have been used for years and have provided a certain degree of satisfaction to its users. However, these methods and systems have been known to suffer from several drawbacks, including the discomfort to the patient caused by the presence of two distinct appointments. There thus remained room for improvements.